USGS Preliminary Analysis_LERZ_7-15-18_v1.1

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of lava at a time -averaged discharge rate (for the entire eruption) of 94 m3/s. (See Appendix A for brief overviews of the 1840, 1955, and 1960 eruptions, as well as the 1924 intrusion.) A glance around the LERZ finds numerous large pyroclastic cones indicating repeated activity in this area. Pu'u Kaliu, which borders the southern edge of Leilani Estates, and a younger vent complex which overlies it, are both very close to the location of the current fissures. Both of these older eruptions are thought to have produced about 200 x 106 m3 of lava (Moore, 1992). Other eruptions in the area, including flows erupted in the late 1700s, may have similar volumes. Perhaps eruptions in the LERZ only continue until pressure in the magmatic system, partly controlled by vent elevation, becomes too low to keep the eruption going. The volume of the current eruption has exceeded that of these older nearby eruptions. The steady discharge from fissure 8 shows no sign of waning supply, suggesting relatively constant magma pressure; the lack of significant ground deformation in this area shows that there is neither storage nor withdrawal from the May intrusion since its initial emplacement. If the ongoing eruption maintains its current style of activity at a high eruption rate, then it may take months to a year or two to wind down. While this seems to be the most likely outcome, a pause in the eruption, followed by additional activity, cannot be ruled out, nor can an abrupt cessation or a transition to steady, longer -lived activity at a lower effusion rate. The shield complex of Heiheiahulu, 9.5 km (6 mi) upslope, represents a more voluminous eruption that could have lasted several years (Moore, 1992), similar to the 35 -year-long eruption of Pu'u 'O'o. Both of these eruptions started with several short 'a'5 flows erupted along a 3.5 km (2.2 mi-) and 7 km -(4.3 mi-) long fissure system, respectively, before centralizing to a single vent (Moore, 1992; Wolfe et al, 1988) and eventually erupting tube -fed pahoehoe flows. The 2018 LERZ eruption has erupted only 'a'5 flows so far but the eruption rate is high and a stable channel system is being elevated by frequent spillovers of pahoehoe flows above Kapoho Crater. The flow maintains its 'a'5 character below that point to the ocean with a more pasty lava oozing from its interior along its edges. The change in the character of the channel toward pahoehoe may signal a gradual change of eruption style and a potentially longer eruption with more destruction of infrastructure. Acknowledgments Many people contributed ideas and comments to early drafts of this manuscript. Christina Neal, Margaret Mangan, Matt Patrick, Carolyn Parcheta, and Steve Brantley of the U.S. Geological Survey Hawaiian Volcano Observatory provided excellent comments on an earlier version of the manuscript and we thank them profusely. References Coan, T., 1841, "Letter from Mr. Coan, Dated at Hilo, 25th Sept. 1849," Missionary Herald, Vol. XXXVII, July 1841, p. 281-285. Hawaiian Volcano Observatory website, "The May 1924 Explosive Eruption of Kilauea," https://volcanoes.usgs.gov/volcanoes/kilauea/geo_hist_1924_halemaumau.html Hawaiian Volcano Observatory, 2017, Preliminary Analysis of Hazards at the Kamokuna Ocean Entry: U.S. Geological Survey Cooperator Report to U.S. Coast Guard. 10